Surface Acoustic Wave (SAW) devices have been used both individually and in arrays as sensors and for materials characterization in a variety of applications ranging from gases/vapors to biological systems. Recently, the SAW device was developed. The hexagonal SAW permits rapid and simultaneous extraction of multiple film parameters of a thin film material, which achieves a more complete characterization than a single SAW device. In sensor applications, this capability allows for enhanced discrimination of an analyte and more accurate quantification. The design of the hexagonal SAW consists of three bi-directional SAW delay lines fabricated on a die. The delay lines are arranged about the center of the die and intersect at its center, producing a single region for sensor analysis. The central region where the acoustic waves intersect is shorted to reduce the number of modes of waves traversing the surface. In this manner, enhanced sensing and materials characterization is attained.
SAW devices have been used in many sensor applications in both gaseous and liquid environments. Each application has its own requirements. For example, the use of a SAW device as a biosensor implies that the device must not inherently be attenuated by the environment it operates in. This implication restricts SAW biosensors to Sheer Horizontal-SAW (SH-SAW) devices and a specialized SH-SAW device that creates a Love-mode wave from a thin film deposited on its surface.
SAW sensors work well as high sensitivity biosensors; however, as with all other biosensors, non-specifically bound (NSB) protein interactions can interfere with sensor response and concentration determination. NSB protein interaction can cause, among other problems, exaggerated response due to multi-layer formation, false responses due to miscellaneous proteins covering the surface, and no response due to poor alignment of the functional groups. Minor improvements to biosensor responses can be achieved by a thorough rinsing, use of ultrasonic baths, and pretreatment of the analyte containing fluids. However, each of these processes adds to the complexity of the creation and use of the biosensor and decreases the functionality of a biosensor operated without specialized training in everyday environments. Developments in acoustic wave applications have demonstrated NSB protein removal with relatively low power consumption thus significantly decreasing the uncertainty of the sensors response.
SAW devices known in the art lack the ability to remove NSB proteins while also detecting biological species. An improved sensor is needed in the art that provides simultaneous sensing and removal of NSB proteins. The improved sensor needs to improve sensitivity and selectivity while simultaneously removing NSB proteins. However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified need could be fulfilled.